Inkjet-printed interdigitated cells for photoelectrochemical oxidation of diluted aqueous pollutants

Planar, interdigitated photoelectrochemical cells were made by inkjet printing. The electrode fingers had widths ranging from 200 to 1500 µm and were revealed by printing a positive protective polymer mask on fluorine-doped tin oxide-coated glass slides and subsequent etching. One finger family was overprinted by an ink-jettable sol–gel composition based on titanium propoxide which was then converted into TiO2 by annealing in air. An incident photon to current conversion efficiency of 0.19 was obtained at 360 nm for 200-nm-thick films. The influence of electrode geometry and titania thickness on the electrochemical properties of resulting cells is discussed in detail. Due to the interdigitated layout, photoelectrochemical response was not suffering from iR drop down to low electrolyte ionic strengths. The printed cells were used in photoelectrocatalytic degradation experiments of aqueous solutions of benzoic acid by broadband ultraviolet irradiation (UVA) and electric bias of 1 V and delivered considerable acceleration of the degradation process compared to the plain photocatalytic mode.